Autogenous submerged liquid diffusion welding of titanium

Abstract

In some embodiments, a method may bond titanium to an intermediate alloy. The method may include layering a portion of an intermediate alloy onto a portion of titanium. The method may include focusing a controlled heat source on a spot of the intermediate alloy to form a weld pool in the intermediate alloy at the spot. The method may include superheating the intermediate alloy in the weld pool above the melting point of the intermediate alloy but below the melting point of titanium such that liquid intermediate alloy contacts the surface of the portion of the titanium heating the portion of the titanium. The method may include diffusing the portions of titanium and intermediate alloy together such that upon the intermediate alloy cooling below the melting point of the intermediate alloy the portions of the intermediate alloy and titanium are bonded forming a weldment.

Description

BACKGROUND OF THE INVENTION1. Field of the Invention[0001]The present disclosure generally relates to systems and methods directed towards autogenous submerged liquid diffusion welding. More particularly, the disclosure generally relates to systems and methods directed towards autogenous submerged liquid diffusion welding of dissimilar metals which are historically difficult to weld.2. Description of the Relevant Art[0002]Titanium and its alloys represent the strongest and lightest alloys available today. Titanium offers superior strength per unit weight as well as unparalleled corrosion resistance not found in any commercially viable metals which are typically used for salt water and other corrosive environments (e.g., oxidizing).[0003]Titanium is a highly reactive material and readily reacts with oxygen, nitrogen and hydrogen and many other elements especially at typical brazing and welding temperatures. Contamination of titanium is associated with undesirable physical and corrosi...

AI Technical Summary

Benefits of technology

[0008]High temperature welding of titanium directly to dissimilar metals has a very limited number of alloy options. This is due to the reactive nature of titanium and the formation of intermetallic compounds that weaken the physical and corrosion resistant characteristics of titanium. The ability to create high strength bonds between titanium and an increased number of alloys extends the use of titanium and allows metals with different characteristics to be combined with titanium for more versatile products at lower costs.

[0010]In some embodiments, the method includes submersion shielding of titanium at the spot beneath a liquid pool of the intermediate alloy which prohibits atmospheric contamination of titanium at the spot.

[0012]In some embodiments, the method includes superheating the intermediate alloy in the weld pool such that sufficient energy is supplied to exceed the beta-Ti transformation temperature transitioning the portion of the titanium to a body-centered cubic beta-Ti crystal phase resulting in a volumetric expansion of the portion of the titanium which disrupts the oxide layer as the portion of the titanium expands. The expansion of the portion of the titanium may function in concert with the liquid pool of the intermediate alloy to dislodge and interrupt the continuity of the titanium-oxide layer exposing oxide-free titanium to the liquid intermediate allow greatly decreasing diffusion resistance of titanium-oxide.

Problems solved by technology

Titanium offers superior strength per unit weight as well as unparalleled corrosion resistance not found in any commercially viable metals which are typically used for salt water and other corrosive environments (e.g., oxidizing).

Contamination of titanium is associated with undesirable physical and corrosion characteristics.

Uncontrolled alloying or contamination resulting from the heating of titanium above 400 C can lead to undesirable physical characteristics.

It is less effective with dissimilar metals severely limiting alloys compatible with the fusion process.

High temperature welding of titanium directly to dissimilar metals has a very limited number of alloy options.

This is due to the reactive nature of titanium and the formation of intermetallic compounds that weaken the physical and corrosion resistant characteristics of titanium.

In some embodiments, the method includes superheating the intermediate alloy in the weld pool such that sufficient energy is supplied to exceed the beta-Ti transformation temperature transitioning the portion of the titanium to a body-centered cubic beta-Ti crystal phase resulting in a volumetric expansion of the portion of the titanium which disrupts the oxide layer as the portion of the titanium expands.

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